What is a serrated adenoma, and is there any increased risk of malignancy or need for surveillance?
Sessile serrated adenomas are premalignant flat (or sessile), often mucus-covered lesions predominantly seen in the cecum and ascending colon, that are thought to lead to CRC through an (alternate) serrated pathway. This differs from most CRCs, which arise from mutations starting with inactivation of the adenomatous polyposis coli (APC) gene. The serrated pathway has a predilection for the proximal colon. These lesions may be associated with BRAF or k-ras mutations, and CPG island methylation, which can lead to silencing of mismatch repair genes (MLH1), which could result in more rapid progression to malignancy in some individuals.